An automatic value switch for remotely controlling a manual valve has been used practically by being mounted afterward on the existing manual valve. FIG. 6 is a block diagram showing a configuration of an air-driving-type automatic valve switch 310 that uses air supplied from an air source 320 as a driving source, and performs opening and closing operations of a manual valve 330 based on an opening pneumatic pressure signal and a closing pneumatic pressure signal inputted from outside.
The air-driving-type automatic valve switch 310 includes an air motor 311, an air valve control switching valve 312, an opening side switching valve 313, a closing side switching valve 314, an opening side limit switch 315 and a closing side limit switch 316. The air motor 311 is connected to the manual valve 330 so as to be opened or closed. The air valve control switching valve 312 switches an air path of the air motor 311 to any one of an opening side, a closing side, and stopping. The opening side switching valve 313 switches the air valve control switching valve 312 to an opening side based on the opening pneumatic pressure signal. The closing side switching valve 314 switches the air valve control switching valve 312 to a closing side based on the closing pneumatic pressure signal. The opening side limit switch 315 detects an opening side limit of the manual valve 330 and closes the opening side switching valve 313. The closing side limit switch 316 detects a closing side limit of the manual valve 330 and closes the closing side switching valve 314.
The air-driving-type automatic valve switch 310 may provide with an error lamp which indicates an opening and closing state, an air terminal which outputs, to the outside, that the opening and closing state of the manual valve 330 has reached the limit, or the like.
FIG. 7 is a block diagram showing a configuration of a conventional valve opening and closing system 300 using the air-driving-type automatic valve switch 310. The valve opening and closing system 300 includes a site/center switching manual valve 321, which can be manually switched on site, between a site side and a center control room side to perform opening and closing operation of the manual valve 330.
In a case where the opening and closing operation of the manual valve 330 is performed on site, the opening and closing operations of the manual valve 330 can be enabled by manually operating a manual valve for opening and closing operation 322. Specifically, the following operations are performed by manually operating the manual valve for opening and closing operation 322. When the manual valve for opening and closing operation 322 is switched to an opening side, the opening pneumatic pressure signal is inputted to the air-driving-type automatic valve switch 310 via an opening side shuttle valve 323. When the manual valve for opening and closing operation 322 is switched to a closing side, a closing pneumatic pressure signal is inputted to the air-driving-type automatic valve switch 310 via a closing side shuttle valve 324.
When the site/center switching manual valve 321 is switched to a center side, air is supplied to an opening/closing switching electric driving valve 326, and a center selected signal is outputted and transmitted to the center control room 340 via a pneumatic-electro converter 326.
In this state, when the center control room 340 outputs an electric driving valve opening signal, the opening/closing switching electric driving valve 326 is switched to an opening side, the opening pneumatic pressure signal is inputted to the air-driving-type automatic valve switch 310 via the opening side shuttle valve 323. Further, when the center control room 340 outputs an electric driving valve closing signal, the opening/closing switching electric driving valve 326 is switched to a closing side, the closing pneumatic pressure signal is inputted to the air-driving-type automatic valve switch 310 via the closing side shuttle valve 324.
Additionally, when an emergency such as a disaster occurs, it is necessary to quickly close the manual valve 330 for safety. In which case, an electric driving valve for forced closing operation 327 is provided at a front stage of the site/center switching manual valve 321, and a forced closing shuttle valve 328 is provided between the closing side of the opening/closing switching electric driving valve 326 and the closing side shuttle valve 324 so that the center control room 340 can forcibly perform closing operation regardless of a switching state of the site/center switching manual valve 321.
When the center control room 340 outputs a forced closing signal to the electric driving valve for forced closing operation 327, the closing pneumatic pressure signal is inputted to the air-driving-type automatic valve switch 310 from the forced closing shuttle valve 328 via the closing side shuttle valve 324. Accordingly, the air-driving-type automatic valve switch 310 performs a closing operation.